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A global analysis of adaptive evolution of operons in cyanobacteria

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Title A global analysis of adaptive evolution of operons in cyanobacteria
 
Creator MEMON, D
SINGH, AK
PAKRASI, HB
WANGIKAR, PP
 
Subject Comparative genomics
Genome context
Gene packing
Phylogenetic distance
Blue-green algae
MICROBIAL GENOMES
ESCHERICHIA-COLI
PROCHLOROCOCCUS ECOTYPES
PROKARYOTIC GENOMES
FUNCTIONAL GENOMICS
GENE CLUSTERS
PREDICTION
DATABASE
PROTEINS
SEQUENCE
 
Description Operons are an important feature of prokaryotic genomes. Evolution of operons is hypothesized to be adaptive and has contributed significantly towards coordinated optimization of functions. Two conflicting theories, based on (i) in situ formation to achieve co-regulation and (ii) horizontal gene transfer of functionally linked gene clusters, are generally considered to explain why and how operons have evolved. Furthermore, effects of operon evolution on genomic traits such as intergenic spacing, operon size and co-regulation are relatively less explored. Based on the conservation level in a set of diverse prokaryotes, we categorize the operonic gene pair associations and in turn the operons as ancient and recently formed. This allowed us to perform a detailed analysis of operonic structure in cyanobacteria, a morphologically and physiologically diverse group of photoautotrophs. Clustering based on operon conservation showed significant similarity with the 16S rRNA-based phylogeny, which groups the cyanobacterial strains into three clades. Clade C, dominated by strains that are believed to have undergone genome reduction, shows a larger fraction of operonic genes that are tightly packed in larger sized operons. Ancient operons are in general larger, more tightly packed, better optimized for co-regulation and part of key cellular processes. A sub-clade within Clade B, which includes Synechocystis sp. PCC 6803, shows a reverse trend in intergenic spacing. Our results suggest that while in situ formation and vertical descent may be a dominant mechanism of operon evolution in cyanobacteria, optimization of intergenic spacing and co-regulation are part of an ongoing process in the life-cycle of operons.
 
Publisher SPRINGER
 
Date 2014-10-15T15:49:58Z
2014-10-15T15:49:58Z
2013
 
Type Article
 
Identifier ANTONIE VAN LEEUWENHOEK INTERNATIONAL JOURNAL OF GENERAL AND MOLECULAR MICROBIOLOGY, 103(2)331-346
http://dx.doi.org/10.1007/s10482-012-9813-0
http://dspace.library.iitb.ac.in/jspui/handle/100/15196
 
Language en